It’s a scary time right now, and we’re all worried about catching coronavirus. Coronavirus, also known as COVID-19, can often be present in a person without any symptoms—in fact, studies have found that over 45% of people with coronavirus may be asymptomatic. Recently, new information has been published about a possible link between coronavirus and hearing loss. Hearing loss does not make a person more susceptible to coronavirus, but the virus may be causing hearing loss among infected patients.
Coronavirus and hearing loss: What is the link?
A small study published in June in The International Journal of Audiology examined 121 adults from Manchester, England, who were admitted to a hospital for coronavirus. Of the patients sampled, 16 (13.2%) reported that their hearing was worse after contracting coronavirus. Eight reported a deterioration in hearing and eight reported an onset of tinnitus.
“We already know that viruses such as measles, mumps, and meningitis can cause hearing loss, and coronaviruses can damage the nerves that carry information to and from the brain,” said Kevin Munro, professor of audiology and study author. He added that “[i]t is possible, in theory, that COVID-19 could cause problems with parts of the auditory system including the middle ear or cochlea.”
Hearing loss and asymptomatic coronavirus
There are other studies that have found possible links between auditory problems and asymptomatic coronavirus. In an Egyptian study, a researcher gave a hearing test to 20 patients aged 20-50 years with asymptomatic coronavirus infection and compared their hearing test results to 20 people without coronavirus infection.
The researcher found that “COVID-19 infection had deleterious effects on the hair cells in the cochlea,” which are an essential part of the hearing process. Damage to these hair cells can cause hearing loss, and indeed, the patients with asymptomatic coronavirus had worse high-frequency hearing compared to a control group of people without coronavirus. Even without displaying symptoms, coronavirus could result in hearing loss for infected people.
Why does coronavirus cause hearing loss?
There’s so much we still don’t know about this virus, so there’s no certain conclusion yet on why coronavirus (with or without symptoms) might be causing hearing loss in a small percentage of patients.
One theory, as presented by the Egyptian study, is that coronavirus damages the hair cells in the ear. These cells, which live in the inner ear, are vital to hearing and cannot be regrown or replaced once they are lost. If coronavirus is damaging inner ear hair cells, that would certainly impact hearing.
Another possible reason for hearing loss after coronavirus infection has to do with our brains. Our brain is a significant part of the hearing process—the ear hears, but the brain processes and decodes the auditory signals from the ear. Coronavirus has been shown to cause serious neurological issues like headaches, strokes, and seizures, and that could just be the beginning. Scientists and medical experts do not fully know the extent of coronavirus-related brain damage, but it could definitely have a negative effect on hearing.
While further research needs to be done, coronavirus is definitely a serious threat. Soon, we may be adding “hearing loss” to the list of complications from this virus.